Battery and production method thereof

ABSTRACT

According to one embodiment, there is provided a battery having a plurality of current collector tabs extended from a plurality of points of a current collector of at least one electrode of a positive electrode and a negative electrode. The battery further has a lid and a lead. The lead has a current collector tab junctional part connected with the current collector tabs, a lid junctional part fixed to the lid, and a vibration absorber part linking the current collector tab junctional part to the lid junctional part.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Divisional application of U.S. application Ser.No. 13/588,121, filed Aug. 17, 2012 which is a Continuation applicationof PCT Application No. PCT/JP2011/053244, filed Feb. 16, 2011 and basedupon and claiming the benefit of priority from Japanese PatentApplications No. 2010-032952, filed Feb. 17, 2010; and No. 2010-058181,filed Mar. 15, 2010, the entire contents of all of which areincorporated herein by reference.

FIELD

Embodiments described herein relate generally to a battery and aproduction method thereof.

BACKGROUND

Lithium secondary battery has recently been developed as a nonaqueouselectrolyte secondary battery which is small and light, has a highenergy density, and is capable of repeated discharge and charge, withthe development of electronic devices. Lately, it has also been desiredto develop a nonaqueous electrolyte secondary battery capable of fastcharge and high output discharge, which is suitable as a secondarybattery for cars such as a hybrid car and an electric car, or as asecondary battery for electric current storage which is used forelectricity equalization.

It is necessary to take out electric current efficiently in order toimprove a fast charge performance and a high output dischargeperformance of a nonaqueous electrolyte secondary battery. For this aim,it is desirable to derive current collector tabs from multiple points ofan electrode. These current collection tabs are electrically connectedto external terminals equipped on a lid through a lead. The lid furtherhas a safety valve for releasing the pressure.

In one aspect, for example, in a case where a nonaqueous electrolytesecondary battery is loaded in an electric car, when a vibration orimpact is applied to the battery from the outside, vibration of anelectrode in the battery may be transmitted to a lid through a currentcollection tab and a lead, whereby a safety valve may be broken. Inparticular, in a case of a large-sized nonaqueous electrolyte secondarybattery for a car, the electrode is also large, which increases theinfluence of vibration. For this reason, the risk of damage to a safetyvalve becomes large due the transmission of vibration.

JP-A No. 2002-279962 discloses a positive electrode current collectorplate 82 in which an accordion-pressed plate 84 is linked to a fittinghole 91 for fitting a positive electrode terminal through a narrowsection 92. The accordion-pressed plate 84 has folded parts 85A, 85B and85C, and several laminated positive electrodes 87 are inserted into eachfolded parts. The narrow section 92 forms a current collecting path (seeFIG. 13). In the positive electrode current collector 82 in JP-A No.2002-279962, however, the transmission of vibration of the electrode toa positive electrode terminal cannot be inhibited, because the plate 84and the fitting hole 91 are located on almost the same plane surface.

JP-A No. 2003-346771 discloses a current collecting connector 2comprising a body 2 a having an almost trapezoidal form and placedhorizontally at ends of two power generation elements lined up. Thecurrent collecting connector 2 further comprises four electrodeconnecting parts 2 b having long and narrow form and protruding downwardfrom the body 2 a. However, a large space is necessary for setting ofthe current collecting connector 2 in JP-A No. 2003-346771, because theelectrode connecting parts 2 b reach the lower end of an electrode fromthe body, and an energy density of a battery is reduced.

In another aspect, a problem occurs in which a welding yield is lowereddepending on the method used for fixing a lid to a container. Forexample, if positions at which lid is fixed are not constant, not onlybattery sizes but also heights of electrode terminals attached to thelids vary. If the height of the electrode terminal is different fromothers in the single batteries, welding defects easily occur when anassembled battery is produced by welding the electrode terminals of thesingle batteries to electrically connect them. As a result, a weldingyield is reduced. In addition, when an electrode terminal is fixed to alid by caulking, the lid may be deformed by the caulking. When the lidis deformed, the degree of fitting between the lid and a case isdegraded, and a gap is easily generated between the lid and the case. Asa result, a welding yield is reduced in a welded part between the lidand the case.

A method for producing an angular sealed battery of JP-A No. 9-7557 isgenerally used for an alkali secondary battery such as a nickel-hydrogensecondary battery. According to JP-A No. 9-7557, when a fitted partbetween an opening end of a container and a lid plate is laser welded toseal the fitted part, a lid plate having a taper peripheral edge isused.

In a sealed battery in JP-A No. 10-144268, an inner peripheral edge ofan opening part of a container is formed as a hole side taper, which isopened out, to receive a lid, and an outer periphery of the lid isformed as an axis side taper to fit in the taper of the opening part.Both tapers are formed so that the welding for joining the lid and thecontainer can be performed from a direction toward a top surface of thelid, when the lid is fitted in the opening part of the container.According to JP-A No. 10-144268, the joined part between the lid and thecontainer is welded from a direction toward the top surface of the lidin the state in which the lid is fitted in the opening part of thecontainer.

In JP-A No. 9-7557 and JP-A No. 10-144268, the lids have the taperperipheral edge and do not have flanges. If an electrode terminal isfixed by caulking to the lid having such a shape, a position of the lidin the container easily varies when the lid is deformed by the caulking.

JP-A No. 2000-156219 illustrates, in FIG. 2, a sealed battery using alid body with a flange. In the battery according to JP-A No.2000-156219, the electrode terminal is hermetically sealed to the lidbody via an insulating material. Thus, the problem of deformation of thelid body caused by the caulking does not occur in the battery accordingto JP-A No. 2000-156219.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of a main part of a batteryaccording to a first embodiment;

FIG. 2 is a perspective view of a lead used in the battery according tothe first embodiment;

FIG. 3 is a perspective view showing a main part of a battery accordingto a second embodiment;

FIG. 4 is a perspective view of a lead used in the battery according tothe second embodiment;

FIG. 5 is a perspective view showing a lid on which the positive andnegative electrode leads shown in FIG. 4 are fixed;

FIG. 6 is a perspective view showing a main part of an electrode grouphaving current collector tabs to which middle leads are joined;

FIG. 7 is a perspective view showing a main part of a battery accordingto another aspect in the second embodiment;

FIG. 8 is a perspective view showing a main part of an electrode grouphaving current collector tabs to which middle leads are not joined;

FIG. 9 is a perspective view of a lead used in a battery according to athird embodiment;

FIG. 10A is a top view of an angular battery according to a fourthembodiment;

FIG. 10B is a cross-sectional view of a main part of the angular batteryaccording to the fourth embodiment, which is cut along a long sidedirection;

FIG. 10C is a cross-sectional view of a main part of the angular batteryaccording to the fourth embodiment, which is cut along a short sidedirection;

FIG. 11A is a top view of an angular battery according to a fifthembodiment;

FIG. 11B is a cross-sectional view of a main part of the angular batteryof the fifth embodiment, which is cut along a long side direction;

FIG. 11C is a cross-sectional view of a main part of the angular batteryaccording to the fifth embodiment, which is cut along a short sidedirection;

FIG. 12A is a top view of a lid used in the angular battery according tothe fifth embodiment;

FIG. 12B is a cross-sectional view of the lid used in the angularbattery according to the fifth embodiment, which is cut along a longside direction;

FIG. 12C is a cross-sectional view of the lid used in the angularbattery according to the fifth embodiment, which is cut along a shortside direction;

FIG. 13A is a top view of an opening-sealing member used in the angularbattery according to the fifth embodiment;

FIG. 13B is a cross-sectional view of the opening-sealing member used inthe angular battery according to the fifth embodiment, which is cutalong a long side direction;

FIG. 13C is a cross-sectional view of the opening-sealing member used inthe angular battery according to the fifth embodiment, which is cutalong a short side direction;

FIG. 14 is a perspective view showing a lead used in Comparative Example1;

FIG. 15 is a top view of a lid used in an angular battery according toComparative Example 3;

FIG. 16 is a top view of an opening-sealing member used in the angularbattery according to Comparative Example 3;

FIG. 17A is a top view of the angular battery of Comparative Example 3;

FIG. 17B is a cross-sectional view of the angular battery according toComparative Example 3, which is cut along a long side direction;

FIG. 17C is a cross-sectional view of the angular battery according toComparative Example 3, which is cut along a short side direction;

FIG. 18 is a top view of a lid used in an angular battery according toComparative Example 4;

FIG. 19 is a top view of an opening-sealing member used in an angularbattery according to Comparative Example 4;

FIG. 20A is a top view of the angular battery according to ComparativeExample 4;

FIG. 20B is a cross-sectional view of the angular battery according toComparative Example 4, which is cut along a long side direction; and

FIG. 20C is a cross-sectional view of the angular battery according toComparative Example 4, which is cut along a short side direction.

DETAILED DESCRIPTION

In general, according to one embodiment, there is provided a batterycomprising a container; an electrode group comprising a positiveelectrode and a negative electrode and being accommodated in thecontainer; a plurality of current collector tabs extended from aplurality of points of a current collector of at least one electrode ofthe positive electrode and the negative electrode in the electrodegroup; a lid closing an opening part of the container; a lead comprisinga current collector tab junctional part connected with the currentcollector tabs electrically, a lid junctional part fixed to the lid, anda vibration absorber part linking the current collector tab junctionalpart to the lid junctional part; and a safety valve equipped on the lid.

According to another embodiment, there is provided a production methodof an angular battery. The battery comprises an angular tube-shapedmetal container having a bottom; a positive electrode and a negativeelectrode accommodated in the container; a lid placed on an opening partof the container; and a terminal fixed to the lid by caulking andconnected to the positive electrode or the negative electrodeelectrically. The lid comprises a bottom placed in the opening part ofthe container, and a stair part located above the bottom and protrudingoutward beyond the bottom. The method comprises placing the bottom ofthe lid in the opening part of the container accommodating the positiveelectrode and the negative electrode, and placing the stair part of thelid on an upper end of a side wall of the container; and irradiating alaser from a direction vertical to a surface at which the stair part ofthe lid is overlaid on the upper end of the side wall of the containerto weld the stair part of the lid to the upper end of a side wall of thecontainer by laser welding.

Battery in embodiments will be explained below, referring to thedrawings. The embodiments are not limited to these embodiments.

First Embodiment

FIG. 1 is an exploded perspective view of a sealed angular nonaqueouselectrolyte secondary battery. This battery has a container 1, anelectrode group 2 accommodated in the container 1, a nonaqueouselectrolyte solution (not shown in the drawing) contained in thecontainer 1, a lid 5 closing an opening part of the container 1, apositive electrode terminal 6 and a negative electrode terminal 7equipped on the lid 5, and a safety valve 21 equipped on the lid 5.

The container 1 is an angular tube-shaped exterior can having a bottom.The container 1 can be formed from, for example, a metal such asaluminum, aluminum alloy, iron or stainless steel.

The electrode group 2 has a flat shape, and contains a positiveelectrode, a negative electrode, and a separator located between thepositive electrode and the negative electrode. The electrode group 2 isproduced, for example, by spirally winding a laminate in which theseparator is sandwiched between the positive electrode and the negativeelectrode, and subjecting the resulting product to a pressure molding.The electrode group 2, which has been spirally wound, is fixed with abinding off tape.

The positive electrode has a positive electrode current collector, apositive electrode active material layer, and a positive electrodecurrent collector tab 8. The positive electrode current collector has abelt-like shape. The positive electrode active material layer is formedon at least one surface of the positive electrode current collector. Thepositive electrode current collector tab 8 has a strip shape whichextends from multiple points on long sides of the positive electrodecurrent collector in a short side direction.

The negative electrode has a negative electrode current collector, anegative electrode active material layer, and a negative electrodecurrent collector tab 9. The negative electrode current collector has abelt-like shape. The negative electrode active material layer is formedon at least one surface of the negative electrode current collector. Thenegative electrode current collector tab 9 has a strip shape whichextends from multiple points on long sides of the negative electrodecurrent collector in a short side direction.

The positive and negative electrode current collector tabs 8, 9 may beeach formed by punching the current collectors. The current collectorsand the current collector tabs are formed from, for example, a metalfoil. The thickness of the metal foil, i.e., the thickness of onecurrent collector tab is desirably from 5 μm or more and 50 μm or less.When the thickness is 5 μm or more, breakage of the current collectorand the current collector tab during production can be prevented, andhigh current collection efficiency can be realized. The melting of thecurrent collector tab which occurs when a large electric current flowscan also be avoided. When the thickness is 50 μm or less, the number ofwindings of the laminate can be increased while the increase of thethickness of the electrode group is inhibited. The thickness of themetal foil is preferably 10 μm or more and 20 μm or less. The materialof the metal foil is selected depending on the kind of the activematerial used in the positive electrode and the negative electrode, andfor example, aluminum, aluminum alloy, copper or copper alloy may beused.

The multiple positive electrode current collector tabs 8 are sandwichedtogether by a positive electrode backup lead 14 which is bent in aU-shaped form.

This positive electrode backup lead 14 is also referred to as a“positive electrode protecting lead.” Similarly, the negative electrodecurrent collector tabs 9 are sandwiched together by a negative electrodebackup lead 15 which is bent in a U-shaped form. The negative electrodebackup lead 15 is also referred to as a “negative electrode protectinglead.”

The positive electrode backup lead 14 is electrically connected to thepositive electrode current collector tab 8, and the negative electrodebackup lead 15 is electrically connected to the negative electrodecurrent collector tab 9 by a method such as laser welding, ultrasonicjoining or resistance welding, preferably by the ultrasonic joining. Thepositive and negative electrode backup leads 14 and 15 are desirablyformed from the same materials as those of the current collector tabs 8,9 of the positive and negative electrodes, respectively. The positiveand negative electrode backup leads 14 and 15 desirably have a thicknessthree times or more that of either of one positive electrode currentcollector tabs 8 or one negative electrode current collector tab 9,respectively. The thickness is more preferably in the range of 0.05 mmor more and 0.6 mm or less, further more preferably 0.1 mm or more and0.5 mm or less.

An opening part of the container 1 is sealed with an opening-sealingmember 10. The opening-sealing member 10 includes the positive electrodeterminal 6, the negative electrode terminal 7, gaskets 13, the lid 5, apositive electrode inner insulator 53, a negative electrode innerinsulator 54, a positive electrode lead 3 and a negative electrode lead4. Rectangular depressions 19 are provided in an outside surface of thelid 5 for storing the gaskets 13 therein. The positive electrodeterminal 6 is stored in one depression 19 through the gasket 13, and thenegative electrode terminal 7 is stored in the other depression 19through the gasket 13. A through hole 20 is formed in each depression19. An inlet 17 for introducing an electrolyte solution is opened in thelid 5, and after the electrolyte solution is introduced, the inlet issealed with a sealing lid 18.

The positive electrode lead 3 and the negative electrode lead 4 areplaced inside the container 1. The positive and negative electrode leads3 and 4 have current collector tab junctional parts 3 b and 4 b toelectrically connect the positive and negative electrode leads 3 and 4to the current collector tabs 8, 9; lid junctional parts 3 a and 4 a tofix the positive and negative electrode leads 3 and 4 to lid 5; andvibration absorber parts to link the current collector tab junctionalparts 3 b and 4 b to the lid junctional parts 3 a and 4 a.

FIG. 2 shows the positive or negative electrode lead 3 (4) used in thebattery of the first embodiment. FIG. 2 shows the positive or negativeelectrode lead 3 (4) in an opposite direction to an installing directionof the lead in the battery, and thus the lid junctional part 3 a (4 a)is located below. The positive and negative electrode lead 3 (4) havethe lid junctional part 3 a (4 a), the current collector tab junctionalpart 3 b (4 b) and the vibration absorber part 3 c (4 c). The lidjunctional part 3 a (4 a) has an almost rectangular plate-like shapewhose one corner is chamfered. The current collector tab junctional part3 b (4 b) has a rectangular plate-like shape. The area of the lidjunctional part 3 a (4 a) is smaller than that of the current collectortab junctional part 3 b (4 b). The vibration absorber part 3 c (4 c) hasa rectangular plate-like shape, and is located between the lidjunctional part 3 a (4 a) and the current collector tab junctional part3 b (4 b).

The positive and negative electrode lead 3 (4) are bent at an almostright angle along a side separating the vibration absorber part 3 c (4c) from the lid junctional part 3 a (4 a). The vibration absorber part 3c (4 c) is placed almost perpendicularly to the lid junctional part 3 a(4 a) by this placement. The vibration absorber part 3 c (4 c) and thecurrent collector tab junctional part 3 b (4 b) are located on the sameplane. Thus, the current collector tab junctional part 3 b (4 b) islocated almost perpendicularly to the lid junctional part 3 a (4 a).

The length X1 of the vibration absorber part 3 c (4 c) in a longerdirection is shorter than the length Y1 of the current collector tabjunctional part 3 b (4 b) in a longer direction, and shorter than thelength W1 of the lid junctional part 3 a (4 a) in a longer direction. Inthis regard, the term “longer direction” refers to a direction crossingat a right angle to an extending direction of the positive or negativeelectrode current collector tab 8 or 9. The shapes of the lid junctionalpart 3 a (4 a), the current collector tab junctional part 3 b (4 b) andthe vibration absorber part 3 c (4 c) are not limited to the rectangularor almost rectangular shape, and can be a square shape. In any shape,the length of the vibration absorber part 3 c (4 c) in the longerdirection is shorter than the lengths of the lid junctional part 3 a (4a) and of the current collector tab junctional part 3 b (4 b) in thelonger direction.

The lid junctional part 3 a has a through hole 3 e. This through hole 3e is the hole for installing an axis of the positive electrode terminal6. The lid junctional part 4 a has a through hole 4 e. This through hole4 e is the hole for installing an axis of the negative electrodeterminal 7.

As shown in FIG. 1, with regard to the positive electrode lead 3, thelid junctional part 3 a is laid on the inner insulator 53, which isplaced on an inner surface of the lid 5. The current collector tabjunctional part 3 b extends downward from a bent part between it and thelid junctional part 3 a. With regard to the negative electrode lead 4,the lid junctional part 4 a is laid on the inner insulator 54, which isplaced on an inner surface of the lid 5. The current collector tabjunctional part 4 b extends downward from a bent part between it and thelid junctional part 4 a.

The inner insulator 53 for the positive electrode may have a rectangularplate-like shape. The inner insulator 53 for the positive electrode hasa through hole 53 a which communicates with the through hole 20 of thelid 5 and with the through hole 3 e of the positive electrode lead 3.The inner insulator 53 for the positive electrode is placed between theinner surface of the lid 5 and the lid junctional part 3 a of thepositive electrode lead 3, and insulates the lid 5 and the positiveelectrode lead 3.

The inner insulator 54 for the negative electrode may have a rectangularplate-like shape. The inner insulator 54 for the negative electrode hasa through hole 54 a which communicates with the through hole 20 of thelid 5 and with the through hole 4 e of the negative electrode lead 4,and a through hole 54 b which communicates with the inlet forintroducing a solution 17 of the lid 5. The inner insulator 54 for thenegative electrode is placed between the inner surface of the lid 5 andthe lid junctional part 4 a of the negative electrode lead 4, andinsulates the lid 5 and the negative electrode lead 4.

The positive electrode terminal 6 has a rivet-like shape, andspecifically it has a flange 6 a and an axis 6 b which extends from theflange 6 a. The axis 6 b of the positive electrode terminal 6 isinserted into the through hole 20 of the lid 5 through the gasket 13,and is also inserted into the through hole 53 a of the inner insulator53 and the through hole 3 e of the positive electrode lead 3. The axisis fixed to them by caulking. Similarly, the negative electrode terminal7 has a rivet-like shape, and specifically it has a flange 7 a and anaxis 7 b which extends from the flange 7 a. The axis 7 b is insertedinto the through hole 20 of the lid 5 through the gasket 13, and is alsoinserted into the through hole 54 a of the inner insulator 54 and thethrough hole 4 e of the negative electrode lead 4. The axis is fixed tothem by caulking. Thus, the positive and negative electrode terminals 6and 7, and the lid 5 are fixed in a state in which the insulation andthe air tightness are secured. In addition, the positive and negativeelectrode terminal 6 and 7 are fixed to the positive electrode lead 3and the negative electrode lead 4, respectively, in a state in which anelectrical connection is secured.

The positive electrode backup lead 14, which grips a tip of the positiveelectrode current collector tab 8, is fixed to the current collector tabjunctional part 3 b of the positive electrode lead 3 in a state in whichan electric connection is maintained. On the other hand, the negativeelectrode backup lead 15, which grips a tip of the negative electrodecurrent collector tab 9, is fixed to the current collector tabjunctional part 4 b of the negative electrode lead 4 in a state in whichan electric connection is maintained.

The electric connection of the positive electrode lead 3 with thepositive electrode backup lead 14, and the electric connection of thenegative electrode lead 4 with the negative electrode backup lead 15 maybe performed by using a method such as laser welding, ultrasonicjoining, or resistance welding. The connection may be preferablyperformed by the ultrasonic joining.

The lid 5 has a rectangular plate-like shape. The lid 5 is welded to anopening part of the container 1, for example, by seam welding with alaser. The lid 5 may be formed from a metal such as aluminum, aluminumalloy, iron or stainless steel. The lid 5 is desirably formed from thesame kind of metal as that of the container 1.

The lid 5 has the safety valve 21 for releasing an inner pressure of thebattery. The safety valve 21 is a rectangular depression. A cross-shapedgroove 22 is formed on a bottom of the depression. This part of thegroove 22 is thin. The shape of the safety valve is not limited to thisshape, and may be any shape so long as it is capable of releasing gas tothe outside by breakage caused by the increased internal pressure of thecontainer.

The gasket 13 is formed from, for example, polypropylene (PP), afluorine-containing thermoplastic resin, or the like. Examples for thefluorine-containing thermoplastic resin includetetrafluoroethylene-perfluoroalkoxyethylene copolymer (PFA),tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and the like.

The positive electrode terminal 6 and the negative electrode terminal 7are formed from, for example, aluminum or aluminum alloy. In a case of alithium ion secondary battery using a carbon material as the negativeelectrode active material, aluminum or aluminum alloy can be used as amaterial for the positive electrode terminal, and a metal such ascopper, nickel or a nickel-plated iron can be used as a material for thenegative electrode terminal.

The positive electrode lead 3 is formed from an electrically conductivematerial. As such a material, for example, aluminum or aluminum alloymay be used. The material can be arbitrarily changed depending on thekind of the positive electrode active material.

The negative electrode lead 4 is formed from an electrically conductivematerial. As such a material, aluminum or aluminum alloy may be usedwhen the negative electrode active material is lithium titanate. Thematerial can be arbitrarily changed depending on the kind of thenegative electrode active material.

The electrode group 2 is vibrated in the container 1 when an impact orvibration is applied to the nonaqueous electrolyte secondary batteryfrom the outside, for example, in the case it loaded into an electriccar. The vibration is transmitted to the lid 5 through the positive andnegative electrode current collector tabs 8 and 9, and the positive andnegative electrode leads 3 and 4. In the nonaqueous electrolytesecondary battery of the first embodiment described above, however, thepositive and negative electrode leads 3 and 4 have the vibrationabsorber parts 3 c and 4 c. The vibration absorber parts 3 c and 4 c canabsorb the vibration. Hence, the transmission of the vibration to thelid 5 can be inhibited; as a result, breakage of the safety valve 21equipped on the lid 5 due to the vibration can be suppressed.

Further, since the vibration is not transmitted to the lid and thusthere is no risk of breakage of the safety valve in the battery of thefirst embodiment, it is possible to join the positive and negativeelectrode current collector tabs 8 and 9 to the current collector tabjunctional parts 3 b and 4 b of the positive and negative electrodeleads 3 and 4 by ultrasonic joining, respectively. This eliminates awelding step of a middle lead to the current collector tab, and thus thenumber of production steps can be decreased. Further, because the middlelead is unnecessary, the number of the parts can be decreased and theweight energy density of the battery can be improved.

The lead used in the battery of the first embodiment preferably has ashape satisfying the following formula (1):

0.12≦X1/Y1≦0.2  (1)

wherein X1 is a length of the vibration absorber part 3 c and 4 c in adirection crossing at a right angle to an extending direction of thecurrent collector tab 8 and 9; and Y1 is a length of the currentcollector tab junctional part 3 b and 4 b in a direction crossing at aright angle to an extending direction of the current collector tab 8 and9. As illustrated in FIG. 2, X1 is a length of the vibration absorberpart 3 c (4 c) in a longer direction. Y1 is a length of the currentcollector tab junctional part 3 b (4 b) in a longer direction.

The vibration absorber part satisfying X1/Y1 of 0.2 or less is low inrigidity, and can sufficiently absorb the vibration. When X1/Y1 is 0.12or more, the strength of the lead can be maintained appropriately.

When the lead which satisfies the formula (1) described above and has ashape such that it is bent along the side separating the vibrationabsorber part from the lid junctional part is used, it can be furtherinhibited from transmitting the vibration of the electrode group to thelid through the current collector tabs, and thus breakage of the safetyvalve can be further suppressed. In addition, the lead having the shapedescribed above has a resistance value which is almost the same as thatof a lead having no vibration absorber part, and thus it can provide anexcellent battery performance.

The length of the vibration absorber part in a longer direction ispreferably a length sufficient to maintain the strength of the lead.This can prevent breakage of the lead.

A length M1 of the vibration absorber part in a direction crossing at aright angle to the longer direction is not particularly limited, and canbe, for example, from 0.8 to 1.2 mm. The transmission of the vibrationcan be inhibited with an increase in the value of M1. The value of M1may be arbitrarily determined depending on the space in which the leadis set and the strength of the lead.

The sizes of the lead, as shown in FIG. 2, including X1, Y1, a length ofthe lid junctional part 3 a (4 a) in a longer direction (W1), a lengthof the lid junctional part 3 a (4 a) in a direction crossing at a rightangle to the longer direction (R1), and a length of the currentcollector tab junctional part 3 b (4 b) in a direction crossing at aright angle to the longer direction (Z1) are not particularly limited,and they may be arbitrarily determined depending on the sizes of thebattery and the electrode, and the like.

The thickness of the lead is not particularly limited, and can be, forexample, from 0.5 to 1 mm. The transmission of the vibration can beinhibited with an increase in the thickness of the lead. The thicknessof the lead may be arbitrarily determined depending on the space inwhich the lead is set and the strength of the lead.

According to the embodiment described above, there can be provided anonaqueous electrolyte battery with breakage of the safety valveequipped on the lid caused by the transmission of the vibration to thelid of the battery is prevented.

Second Embodiment

Next, a nonaqueous electrolyte secondary battery of a second embodimentwill be explained referring to FIG. 3. In FIG. 3, the same numbers asthose in FIGS. 1 and 2 described above denote the same members and theexplanations thereof are omitted. FIG. 4 is a perspective view showing apositive and negative electrode leads 3 and 4 used in the battery shownin FIG. 3.

The positive and negative electrode lead 3 (4) has a lid junctional part3 a (4 a), a current collector tab junctional part 3 b (4 b), and avibration absorber part 3 c (4 c). The vibration absorber part 3 c (4 c)has an almost quadrilateral shape, and is placed along a side in a shortside direction of a container 1. The lid junctional part 3 a (4 a) has arectangular shape, and extends vertically from the vibration absorberpart 3 c (4 c). The lid junctional part 3 a (4 a) is formed by bendingalong a first side 23 of the vibration absorber part 3 c (4 c) (an upperside in FIG. 4). The current collector tab junctional part 3 b (4 b) hasa rectangular shape, and extends vertically from the vibration absorberpart 3 c (4 c). The current collector tab junctional part 3 b (4 b) isformed by bending along a second side 24 of the vibration absorber part3 c (4 c). The first side 23 and the second side 24 are adjacent to eachother. The lid junctional part 3 a (4 a) and the current collector tabjunctional part 3 b (4 b) extend in the same direction. There is a gap25 between the lid junctional part 3 a (4 a) and the current collectortab junctional part 3 b (4 b), and the lid junctional part 3 a (4 a) isnot directly brought into contact with the current collector tabjunctional part 3 b (4 b).

The lid junctional part 3 a has a through hole 3 e. This through hole 3e is the hole for installing an axis of a positive electrode terminal 6.The lid junctional part 4 a has a through hole 4 e. This through hole 4e is the hole for installing an axis of a negative electrode terminal 7.

As shown in FIG. 5, the positive and negative electrode leads 3 and 4are laid on a lid 5 through an inner insulator which is not shown, andare fixed by caulking with the positive and negative electrode terminals6 and 7. Specifically, the lid junctional part 3 a of the positiveelectrode lead 3, the inner insulator (not shown in FIG. 5) and the lid5 are laminated in this order, and the axis of the positive electrodeterminal 6 is inserted into a through hole of the inner insulator andthe through hole 3 e of the lid junctional part 3 a. The positiveelectrode lead 3 is placed so that the longer direction of the currentcollector tab junctional part 3 b is the same as the longer direction ofthe lid 5, and the surface of the vibration absorber part 3 c is almostparallel to the short side direction of the lid 5. The lid junctionalpart 4 a of the negative electrode lead 4, the inner insulator (notshown in FIG. 5) and the lid 5 are laminated in this order, and the axisof the negative electrode terminal 7 is inserted into the through holeof the inner insulator and the through hole 4 e of the lid junctionalpart 4 a. The negative electrode lead 4 is placed so that the longerdirection of the current collector tab junctional part 4 b is the sameas the longer direction of the lid 5, and the surface of the vibrationabsorber part 4 c is almost parallel to the short side direction of thelid 5.

As shown in FIG. 6, positive and negative electrode current collectortabs 8 and 9 are respectively sandwiched by positive and negativeelectrode backup leads 14 and 15 which are bent in U-shaped forms. Thepositive and negative electrode backup leads 14 and 15 are joined to amiddle lead 17 having a rectangular plate-like shape together with thepositive and negative electrode current collector tab 8 and 9,respectively. The positive and negative electrode backup leads 14 and 15may be joined to the middle lead 17 by a method such as laser welding,ultrasonic joining or resistance welding, and are preferably joined bythe ultrasonic joining.

The positive and negative electrode current collector tab 8 and 9 andthe backup leads 14 and 15 are joined to one surface each of the middlelead 17. As shown in FIG. 3, the other surface of the middle lead 17 isjoined to the current collector tab junctional part 3 b or 4 b of thepositive or negative electrode lead. The positive and negative electrodeleads 3 and 4 may be joined to the middle lead 17 by a method such aslaser welding, ultrasonic joining or resistance welding.

The positive and negative electrode leads 3 and 4 used in thisembodiment are, as shown in FIG. 4, bent along a first side 23 whichseparates the vibration absorber part 3 c (4 c) from the lid junctionalpart 3 a (4 a) and bent along a second side 24 which is adjacent to thefirst side 23 and separates the vibration absorber part 3 c (4 c) fromthe current collector tab junctional part 3 b (4 b), The positive andnegative electrode leads 3 and 4 have a gap 25 between the lidjunctional part 3 a (4 a) and the current collector tab junctional part3 b (4 b). When the lead has such a shape, a distance between ajunctional part of the positive and negative electrode leads 3 and 4 tothe lid 5 and a junctional part of the positive and negative electrodeleads 3 and 4 to the positive or negative electrode current collectortab 8 or 9 can be sufficiently large while maintaining a compact sizeenabling them to be accommodated in the container 1, and thus thetransmission of vibration can be inhibited. The nonaqueous electrolytesecondary battery of the second embodiment using such positive andnegative electrode leads 3 and 4 inhibits the transmission of thevibration of an electrode group 2 to the lid 5 through the positive andnegative electrode current collector tabs 8 and 9, and the positive andnegative electrode leads 3 and 4, and thus the breakage of a safetyvalve can be suppressed.

Further, since the vibration is not transmitted to the lid and thusthere is no risk of breakage of the safety valve, it is possible to jointhe positive and negative electrode current collector tab 8 and 9 to thecurrent collector tab junctional part 3 b and 4 b of the positive andnegative electrode lead by ultrasonic joining, respectively. Thus, thenumber of production steps and the number of parts can be decreased.

Since the positive or negative electrode lead 3 (4) having the shapedescribed above has vibration absorber part 3 c (4 c) with a large area,the strength is high and it is hard to break.

The positive or negative electrode lead 3 (4) shown in FIG. 4 has anotch 26 around a corner at which the first side of the vibrationabsorber part 3 c (4 c) intersects the second side, but the lead is notlimited thereto, and may have a shape with no notch.

As shown in FIG. 4, the sizes of the lead include a length (Z2) of thecurrent collector tab junctional part 3 b (4 b) in a direction crossingat a right angle to the extending direction of the current collector tab8 or 9; a length (Y2) of the current collector tab junctional part 3 b(4 b) in an extending direction of the current collector tab 8 or 9; alength (W2) of the lid junctional part 3 a (4 a) in a direction crossingat a right angle to an extending direction of the current collector tab;a length (Q2) of the vibration absorber part 3 c (4 c) parallel to thefirst side; and a length (R2) of the vibration absorber part 3 c (4 c)parallel to the first side of the part at which the notch 26 is located.W2 is a length of the lid junctional part 3 a (4 a) in a longerdirection, which is a length in the same direction as a long sidedirection of the container 1. These sides of the lead are notparticularly limited, and may be arbitrarily determined depending on thesizes of the battery and the electrode, and the like.

The thickness of the lead is not particularly limited, and can be, forexample, from 0.5 to 1 mm. The transmission of vibration can beinhibited with an increase in the thickness of the lead. The thicknessof the lead may be arbitrarily determined depending on the space inwhich the lead is set and the strength of the lead.

Next, a nonaqueous electrolyte secondary battery of another aspect ofthe second embodiment will be explained referring to FIGS. 7 and 8. Inthe battery of this embodiment, positive and negative electrode leads 3and 4 having the shape shown in FIG. 4 are used. The positive andnegative electrode leads 3 and 4 are fixed on a lid 5 in the manner asshown in FIG. 5. As shown in FIG. 7, in the battery of the aspect, thepositive and negative electrode leads 3 and 4 are joined to positive andnegative electrode backup leads 14 and 15, respectively, without havinga middle lead interposed.

As shown in FIG. 8, positive and negative electrode current collectortabs 8 and 9 are respectively sandwiched by positive and negativeelectrode backup leads 14 and 15 which are bent in U-shaped forms. Asshown in FIG. 7, one surface of the positive and negative electrodebackup leads 14 and 15 is respectively joined to a current collector tabjunctional part 3 b and 4 b of the positive and negative electrode leads3 and 4. The joining may be performed by a method such as laser welding,ultrasonic joining or resistance welding, and it is preferably performedby the ultrasonic joining.

Conventionally, when positive and negative electrode leads 3 and 4 wererespectively joined to positive and negative electrode backup leads 14and 15 by ultrasonic joining, vibration was transmitted to a lid,resulting in a risk of breakage of a safety valve. However, the batteryof this embodiment can inhibit the vibration transmitted to the lid, andtherefore, the positive and negative electrode leads 3 and 4 can bejoined respectively to the positive and negative electrode backup leads14 and 15 by ultrasonic joining. As a result, it is possible to decreasethe number of production steps and the number of parts.

According to the embodiment described above, the nonaqueous electrolytebattery which prevents the breakage of the safety valve provided on thelid, caused by the transmission of vibration to the lid of the battery,can be provided.

Third Embodiment

Next, a nonaqueous electrolyte secondary battery of a third embodimentwill be explained referring to FIGS. 3 and 9. In FIG. 9, the samenumbers as those in FIG. 4 described above denote the same members andthe explanations thereof are omitted.

As shown in FIG. 9, a positive or negative electrode lead 3 (4) used inthe nonaqueous electrolyte battery of the third embodiment has a shapewhich is the same as that of the positive or negative electrode lead 3(4) used in the second embodiment, and further has a second vibrationabsorber part 3 d (4 d) which is brought into contact with a second side24. The second vibration absorber part 3 d (4 d) is disposed between apart at which a current collector tab junctional part 3 b (4 b) isjoined to a positive and negative electrode current collector tabs 8 and9 or a middle lead, and a vibration absorber part 3 c (4 c); in otherwords, the second vibration absorber part 3 d (4 d) is not disposed atthe part at which the current collector tab junctional part 3 b (4 b) isjoined to the positive and negative electrode current collector tabs 8and 9 or the middle lead.

The positive and negative electrode leads used in the battery of thethird embodiment preferably satisfy the following formula (2):

0.5≦X2/Y2<1  (2)

wherein X2 is a length of the second vibration absorber part 3 d (4 d)in the same direction as an extending direction of the current collectortabs 8 and 9; and Y2 is a length of the current collector tab junctionalpart 3 b (4 b) in the same direction as the extending direction of thecurrent collector tabs 8 and 9. As illustrating in FIG. 9, X2 shows alength of the second vibration absorber part 3 d (4 d) crossing at aright angle to a longer direction, and Y2 shows a length of the currentcollector tab junctional part 3 b (4 b) crossing at a right angle to alonger direction. The longer direction of the second vibration absorberpart 3 d (4 d) is the same as the longer direction of the currentcollector tab junctional part 3 b (4 b).

The vibration absorber part having X2/Y2 of less than 1 has a lowrigidity and thus can absorb vibration. When X2/Y2 is 0.5 or more, thestrength of lead can be appropriately maintained.

In the lead having the shape described above, a distance between ajunctional part of the lead and lid and a junctional part of the leadand the current collector tab is large while the size is in a compactshape for accommodating them in the container 1. In addition, becausethe lead has the second vibration absorber part 3 d (4 d), thetransmission of vibration can be further inhibited. When the lead havingthe shape described above is used, it is possible to inhibit thetransmission of the vibration of an electrode group to the lid throughthe current collector tab, whereby the breakage of the safety valve canbe suppressed. In addition, because the vibration is not transmitted tothe lid and there is no risk of breakage of the safety valve, it ispossible to join the positive and negative electrode current collectortabs 8 and 9 to the current collector tab junctional part 3 b and 4 b ofthe positive and negative electrode leads 3 and 4 by ultrasonic joining,respectively.

The length M2 of the second vibration absorber part 3 d (4 d) in thelonger direction is not particularly limited, and it can be, forexample, from 4 to 8 mm. The transmission of vibration can be inhibitedwith an increase in the value of M2. The value of M2 may be arbitrarilydetermined depending on the strength of the lead.

As shown in FIG. 9, the sizes of the lead include a length (Z2) of thecurrent collector tab junctional part 3 b (4 b) in a direction crossingat a right angle to an extending direction of the current collector tabs8 and 9; a length (W2) of the lid junctional part 3 a (4 a) in adirection crossing at a right angle to an extending direction of thecurrent collector tab; a length (Q2) of the vibration absorber part 3 c(4 c) in a direction parallel to a first side thereof; and a length (R2)of the vibration absorber part 3 c (4 c) parallel to the first side ofthe part at which the notch 26 is located. W2 is a length of the lidjunctional part 3 a (4 a) in a longer direction, which is a length inthe same direction as a long side direction of the container 1. Thesizes of the lead are not particularly limited, and may be arbitrarilydetermined depending on the sizes of the battery and the electrode, andthe like.

The thickness of the lead is not particularly limited, and can be, forexample, from 0.5 to 1 mm. The transmission of vibration can beinhibited with an increase in the thickness of the lead, and it may bearbitrarily determined depending on the space in which the lead is setand the strength of the lead.

Fourth Embodiment

Next, an angular nonaqueous electrolyte battery according to a fourthembodiment will be explained. As shown in FIGS. 10A, 10B and 10C, thisbattery has a container 31, an electrode group 32 accommodated in thecontainer 31, a nonaqueous electrolyte solution (not shown in thedrawings) contained in the container 31, a lid 33 which closes anopening part of the container 31, and a positive electrode terminal 34and a negative electrode terminal 35 which are equipped on the lid 33.The container 31 has an angular tube shape having a bottom, and is anexterior can formed from, for example, a metal such as aluminum,aluminum alloy, iron or stainless steel.

The electrode group 32 contains a positive electrode (not shown in thedrawings), a negative electrode (not shown in the drawings), and aseparator (not shown in the drawings) which is placed between thepositive electrode and the negative electrode, and has a flat shape. Theelectrode group 32 is produced, for example, by putting the separatorbetween the positive electrode and the negative electrode, spirallywinding them, and then pressure molding them into a flat shape.

As shown in FIG. 10B, a bottom 36 of the lid 33 is defined by athickness from a bottom face to a stair part 37, and is placed insidethe opening part of the container 31. A part located above the bottom 36of the lid 33 is a stair part 37 (hereinafter referred to as a “flange37”) which protrudes outward beyond the bottom. The lid 33 has apositive electrode terminal 34, which projects convexly to the outsidesurface (i.e., the top surface side), and has a through hole. Thenegative electrode terminal 35 is fixed in the through hole by caulking.The lid 33 is formed from, for example, a metal such as aluminum,aluminum alloy, iron or stainless steel. The lid 33 is desirably formedfrom the same metal as the container 31.

As shown in FIGS. 10B and 10C, the negative electrode terminal 35 has arivet-like shape. Specifically, it has a head 35 a, and an axis 5 bwhich extends from the head 35 a. The negative electrode terminal 35 isfixed in the through hole of the lid 33 through an insulating gasket 39by caulking.

A rectangular insulating plate 40 is placed on the bottom face of thelid 33. The insulating plate 40 has a through hole, and the axis 35 b ofthe negative electrode terminal 35 is fixed in the through hole bycaulking.

A rectangular negative electrode lead 41 is placed on an undersurface ofthe insulating plate 40. The negative electrode lead 41 has a throughhole, and the axis 35 b of the negative electrode terminal 35 is fixedin the through hole by caulking.

One end of a negative electrode tab 42 is electrically connected to anegative electrode of the electrode group 32, and the other end thereofis electrically connected to the negative electrode lead 41. When thetab has such a structure, the negative electrode of the electrode group32 is electrically connected to the negative electrode terminal 35 andthe negative electrode lead 41 through the negative electrode tab 42.

The negative electrode terminal 35, the negative electrode lead 41 andthe negative electrode tab 42 are formed from an electrically conductivematerial, and the material is changed depending on the kind of thenegative electrode active material. When the negative electrode activematerial is lithium titanate, aluminum or aluminum alloy may be used.

The rectangular positive electrode lead 43 is electrically connected tothe positive electrode terminal 34 by fixing it on the bottom face ofthe lid 33. One end of the positive electrode tab 44 is electricallyconnected to a positive electrode of the electrode group 32, and theother end thereof is electrically connected to the positive electrodelead 43. When the lead has such a structure, the positive electrode ofthe electrode group 32 is electrically connected to the positiveelectrode terminal 34 and the positive electrode lead 43 through thepositive electrode tab 44.

The positive electrode lead 43 and the positive electrode tab 44 areformed from an electrically conductive material, and the material can bechanged depending on the kind of the positive electrode active material,and for example, aluminum or aluminum alloy may be used.

The bottom 36 of the lid 33 is placed in the opening part of thecontainer 31, and the flange 37 is placed above an upper end of a sidewall 31 a of the container 31. The flange 37 of the lid 33 is welded tothe upper end of the side wall 31 a of the container 31 by laser seamwelding. This enables the container 31 to be air-tightly sealed by thelid 33.

A method for producing the angular battery of the fourth embodiment willbe explained below.

First, the electrode group 32 and other necessary members areaccommodated in the container 31. After the insulating gasket 39 isinserted in the through hole of the lid 33, the axis 35 b of thenegative electrode terminal 35 is inserted into the insulating gasket39, and the through holes of the insulating plate 40 and the negativeelectrode lead 41, and the axis 35 b of the negative electrode terminal35 is deformed to have an enlarged diameter by caulking. As a result,the axis 35 b of the negative electrode terminal 35 is fixed in thethrough hole of the lid 33 through the insulating gasket 39 by caulking,and the insulating plate 40 and the negative electrode lead 41 are fixedon the axis 35 b of the negative electrode terminal 35 by caulking.

The positive electrode of the electrode group 32 is electricallyconnected to the positive electrode terminal 34 of the lid 33 using thepositive electrode tab 44, and the negative electrode of the electrodegroup 32 is electrically connected to the negative electrode terminal 35of the lid 33 using the negative electrode tab 42. The electricalconnection method may include, for example, laser welding, ultrasonicjoining, resistance welding, and the like.

Subsequently, the bottom 36 of the lid 33 is inserted inside the openingpart of the container 31, and the flange 37 of the lid 33 is placed atthe upper end of a side wall 31 a of the container 31. Laser seamwelding is performed by irradiating a laser beam from a tool 45 forwelding to the flange 37 of the lid 33. A direction of radiation L isset so as to be perpendicular to a surface at which the flange 37 of thelid 33 is overlaid on the upper end of a side wall 31 a of the container31. As a result, the flange 37 of the lid 33 is welded on the upper endof a side wall 31 a of the container 31 by laser seam welding.

When the negative electrode terminal 35 is fixed on the lid 33 bycaulking, not only the negative electrode terminal 35 is pressurized inan axial direction to deform to have an enlarged diameter, but also thepressure is applied to a periphery of the through hole. As a result, theside face of the long side of the lid 33 is curved outward on a partcorresponding to the through hole. When the bottom 36 of the thusdeformed lid 33 is inserted into the opening part of the container 31,the bottom 36 of the lid 33 is not fitted to the side wall around theopening part of the container 31, resulting in a gap between them.However, four sides of the flange 37 of the lid 33 are all placed on theupper end of a side wall 31 a of the container 31, and thus, the flange37 can cover the opening part of the container 31. As a result, the gapbetween the bottom 36 of the lid 33 and the opening part, i.e., theinner surface of the side wall of the container 31 is not exposed to theoutside. In addition, when the welding is performed by irradiating alaser toward the surface at which the upper end of a side wall 31 a ofcontainer 31 is overlaid on the flange 37 in a vertical direction,welding defects resulting from the gap can be decreased, and thecontainer 31 can be air-tightly sealed with the lid 33. Furthermore, theposition of the lid 33 toward the container 31 can be determined only byplacing the flange 37 of the lid 33 on the upper end of a side wall 31 aof the container 31, and therefore variation per product in a size suchas a total height of a battery or a height of a positive or negativeelectrode terminal can be reduced.

When a so-called “overpick” is performed, in which the flange 37 of thelid 33 is placed on the upper end of a side wall 31 a of the container31, and a laser is irradiated from a vertical direction toward thesurface at which the flange 37 is overlaid on the container 31, i.e.,from the top surface of the flange 37, generation of cracks can beprevented and splashes can be decreased at a depth of about the wallthickness of the container 31, and accordingly a sufficient pressurecapacity can be obtained. For example, when the wall thickness of thecontainer 31 (i.e., the thickness of the container) is 0.5 mm, about 0.5mm of penetration depth is necessary. On the other hand, a pressurecapacity in a welded part of the lid 33 and the container 31 can beadjusted by the wall thickness of the container 31 and a workingpressure of the safety valve equipped on the lid 33. Therefore, thepenetration to a depth which is the same as or greater than the wallthickness of the container 31 is not necessary and the penetration depthmay be 0.5 mm or less. In addition, in the case of the overpick, awelding apparatus can be biaxially controlled, and thus the processingspeed can be easily increased and the cost of equipment can be reduced.

On the other hand, in a case of a so-called “sidepick” in which weldingis performed from a horizontal direction toward the surface at which theflange 37 of the lid 33 is overlaid on the upper end of a side wall 31 aof the container 31, a problem arises in which the flange 37 is notcompletely melted into the container when a penetration depth is lessthan the wall thickness of the container 31, and cracks are easilygenerated; in other words, a penetration depth which is the same as orgreater than the wall thickness of the container 31 is necessary. Forexample, when the container 31 has a wall thickness of 0.5 mm, apenetration of 0.5 mm or more is necessary. Additionally, in the case ofthe sidepick, a welding apparatus is triaxially controlled, and thus itis hard to increase the processing speed and reduce the cost ofequipment.

As stated above, the penetration depth in the case in which the laser isirradiated from the vertical direction toward the surface at which theflange 37 is overlaid on the container 31 can be made less than that inthe case in which the laser is irradiated from the horizontal directiontoward the overlaid surface. As a result, the laser output can be set ata lower level, and it is advantageous in terms of inhibition of thequantity of splashes generated and an increase in the processing speed.

After the laser welding, an electrolyte solution is injected from aninlet for injecting an electrolyte solution (not shown in the drawing)equipped on the lid 33, and after that the inlet for injecting asolution is sealed with a seal lid (not shown in the drawing), therebyobtaining an angular nonaqueous electrolyte battery. According to such aproduction method, a welding yield can be improved.

The thickness T of the flange 37 of the lid 33 is desirably a thicknesswhich is the same as the wall thickness of the container 31 or less, andit is more preferably within a range of 0.5 mm or less. Thus, a completepenetration depth of the flange 37 which is required in the overpickwelding can be made less than the wall thickness of the container 31,for example, 0.5 mm or less, and thus the laser output can be furtherreduced.

The wall thickness of the container 31 is not particularly limited solong as it is the same as the thickness T of the flange 37 or more.

The welding can be performed using a laser beam such as a carbonic acidgas laser or YAG laser.

In a case of a lithium ion secondary battery using a carbon material asthe negative electrode active material, aluminum or aluminum alloy isgenerally used as the material for the positive electrode terminal, thepositive electrode lead, the positive electrode tab, and the like; and ametal such as copper, nickel or nickel-plated iron is used as thematerial for the negative electrode terminal, the negative electrodelead, the negative electrode tab, and the like.

According to the fourth embodiment, a part of the lid 33 is used as thepositive electrode terminal 34, and the negative electrode terminal 35is attached to the lid 33 by caulking, but a part of the lid 33 may beused as the negative electrode terminal 35, and the positive electrodeterminal 34 may be attached to the lid 33 by caulking. Alternatively,both of the positive and negative electrode terminals 4 and 5 can beattached to the lid 33 by caulking.

According to the embodiment described above, the angular battery havingthe lid with the electrode terminals attached thereto by caulking can beprovided and welding yields can be improved in the production methodthereof.

Fifth Embodiment

An angular nonaqueous electrolyte battery of a fifth embodiment is shownin FIGS. 11A, 11B and 11C. FIG. 11 is a top view of the angular batteryof the fifth embodiment; FIG. 11B is a cross-sectional view of a mainpart of the angular battery, which is cut along a long side direction;and FIG. 11C is a cross-sectional view of a main part of the angularbattery, which is cut along a short side direction. The batteryaccording to this embodiment has the same structure as that of theangular nonaqueous electrolyte battery according to the fourthembodiment, except that a shape of a lid and a method for attaching apositive electrode terminal are different. Hereinafter, In the batteryof the fifth embodiment, the same numbers as those in the fourthembodiment denote the same members and the explanations thereof areomitted.

As shown in FIGS. 11A, 11B and 11C, in the battery according to theembodiment, a positive electrode terminal 34 is fixed on a lid 33 bycaulking together with a negative electrode terminal 35.

As shown in FIGS. 12A, 12B and 12C, the lid 33 has a through hole 38 towhich the negative electrode terminal 35 is fixed by caulking, and athrough hole 46 to which the positive electrode terminal 34 is fixed bycaulking. As shown in FIG. 12A, a bottom 36 of the lid 33 has fourdepressions 47 on both side in a long side direction. These fourdepression 47 are placed so that they form a line with the through hole38 or 46 in a short side direction of the lid 33. By this placement, apart in which the through holes 38, 46 are crossed is made shorter thanother parts, in a width of the bottom 36 in a short side direction.

FIGS. 13A, 13B and 13C show an opening-sealing member. Thisopening-sealing member is a member in which the positive and negativeelectrode terminals 34, are attached to the lid 33 having the shapeshown in FIGS. 12A, 12B and 12C by caulking. The opening-sealing membercontains the lid 33, the positive and negative electrode terminals 34and 35, an insulating gasket 39, an insulating plate 40, and positiveand negative electrode leads 43 and 41.

As shown in FIG. 13B, the positive electrode terminal 34 has arivet-like shape. Specifically, it has a head 34 a and an axis 34 bwhich extends from the head 34 a. The positive electrode terminal 34 isfixed in the through hole 46 of the lid 33 through the insulating gasket39 by caulking. Further, the rectangular insulating plate 40, which isplaced on the bottom face of the lid 33, and the rectangular positiveelectrode lead 43, which is placed on the undersurface of the insulatingplate 40, are fixed on the axis 34 b of the positive electrode terminal34 by caulking. When the positive electrode of the electrode group 32has such a structure, it is electrically connected to the positiveelectrode terminal 34 through the positive electrode tab 44 and thepositive electrode lead 43.

As shown in FIGS. 13B and 13C, the negative electrode terminal 35 has arivet-like shape. Specifically, it has a head 35 a and an axis 35 bwhich extends from the head 35 a. The negative electrode terminal 35 isfixed in the through hole 38 of the lid 33 through the insulating gasket39 by caulking. Further, the rectangular insulating plate 40, which isplaced on the bottom face of the lid 33, and the rectangular negativeelectrode lead 41, which is placed on the undersurface of the insulatingplate 40, are fixed on the axis 35 b of the negative electrode terminal35 by caulking. When the negative electrode of the electrode group 32has such a structure, the electrode is electrically connected to thenegative electrode terminal 35 through the negative electrode tab 42 andthe negative electrode lead 41.

As shown in FIG. 13A, when the positive and negative electrode terminals34 and 35 are fixed on the lid 33 by caulking in this embodiment, thebottom 36 of the lid 33 is deformed and protrusions 47′ are generated atpositions corresponding to the through holes 46 and 38. However,protrusion 47 are made in anticipation of the deformation volumes ofthese protrusions 47′, and therefore, the protrusions 47′ fall within arange of the depressions 47. As a result, when the bottom 36 of the lid33 is inserted into an opening part of the container 31, a gap generatedbetween the bottom 36 of the lid 33 and a side wall around the openingpart of the container 31 can be reduced. In addition, the flange 37 cancover the opening part of the container 31 because the lid 33 has theflange 37. Thus, the gap generated between the bottom 36 of the lid 33and the side wall around the opening part of the container 31 is notexposed to the outside. As a result, welding defects resulting from thegap between the lid 33 and the container 31 can be further reduced. Thedeformation of the lid 33 can be reduced because the deformation of thebottom 36 of the lid 33 due to the caulking occurs in the depressions47, and therefore variation per product in a size such as a total heightof a battery or a height of a positive or negative electrode terminalcan be further reduced. In order to assemble an assembled battery fromthe angular batteries, laser welding of bus bars to the positive andnegative electrode terminals 34 and 35 equipped on the lid 33 isnecessary. According to the fifth embodiment, the variation in theheight of the battery can be reduced, and thus a yield of the laserwelding can be improved in the production of the assembled battery.

The lids used in the fourth and fifth embodiments have a shape in whichall parts disposed above the bottom are the flange part, but they arenot limited to this shape, and, for example, it is possible to make astair part having a smaller area than that of the flange at the topsurface of the flange.

According to the embodiment described above, the angular battery havingthe lid with the electrode terminals attached thereto by caulking can beprovided and welding yields can be improved in the production methodthereof.

(Positive Electrode)

The positive electrode used in the first to fifth embodiments will beexplained. The positive electrode can be formed, for example, by coatinga current collector with slurry containing a positive electrode activematerial. The positive electrode active material is not particularlylimited, and oxides, sulfides or polymers capable of occluding andreleasing lithium can be used. Examples of the preferable activematerial include lithium manganese complex oxides, lithium nickelcomplex oxides, lithium cobalt complex oxides, and lithium ironphosphate, which can provide a high positive electrode potential. Thecurrent collector can be formed, for example, from an aluminum foil oran aluminum alloy foil.

(Negative Electrode)

The negative electrode used in the first to fifth embodiments will beexplained. The negative electrode can be formed, for example, by coatinga current collector with slurry containing a negative electrode activematerial. The negative electrode active material is not particularlylimited, and metal oxides, metal sulfides, metal nitrides, alloy orcarbon capable of occluding and releasing lithium can be used. Materialshaving an occlusion and release potential of lithium ion of 0.4 V ormore noble to a metal lithium potential are preferably used. Thenegative electrode active material having such an occlusion and releasepotential of lithium ion can inhibit an alloy reaction of the aluminumor aluminum alloy with the lithium. Therefore, it is possible to usealuminum or aluminum alloy for forming the negative electrode currentcollector and related parts of the negative electrode. Examples of sucha negative electrode active material include titanium oxides, lithiumtitanium oxides, tungsten oxides, amorphous tin oxides, tin siliconoxides, and silicon oxides. Lithium titanium complex oxides areparticularly preferable. The current collector can be formed, forexample, from an aluminum foil or an aluminum alloy foil.

(Separator)

The separator used in the first to fifth embodiments will be explained.As the separator, for example, microporous films, woven fabrics,non-woven fabrics or laminates thereof may be used. The laminate may beformed from the same material or different materials. Examples of thematerial forming the separator include polyethylene, polypropylene,ethylene-propylene copolymers, and ethylene-butene copolymers.

(Electrolyte Solution)

The electrolyte solution used in the first to fifth embodiments will beexplained. A nonaqueous electrolyte solution may be used as theelectrolyte solution. The nonaqueous electrolyte solution can beprepared by dissolving an electrolyte such as a lithium salt in anonaqueous solvent. Examples of the nonaqueous solvent include ethylenecarbonate (EC), propylene carbonate (PC), butylene carbonate (BC),dimethyl carbonate (DMC), diethyl carbonate (DEC), ethylmethyl carbonate(EMC), γ-butyrolactone (γ-BL), sulfolane, acetonitrile,1,2-dimethoxyethane, 1,3-dimethoxypropane, dimethyl ether,tetrahydrofuran (THF) and 2-methyltetrahydrofuran. The nonaqueoussolvent may be used alone or as a mixture of two or more kinds. Examplesof the electrolyte include lithium salts such as lithium perchlorate(LiClO₄), lithium hexafluorophosphate (LiPF₆), lithium tetrafluoroborate(LiBF₄), lithium arsenic hexafluoride (LiAsF₆), and lithiumtrifluoromethasulfonate (LiCF₃SO₃). The electrolyte may be used alone oras a mixture of two or more kinds. The amount of the electrolytedissolved in the nonaqueous solvent is preferably within a range of 0.2mol/L to 3 mol/L.

EXAMPLE Experiment 1

Examples of the embodiment will be explained below. A specimen for testin which a lead fixed on a lid was connected to a backup lead whichsandwiched a current collector tab extended from an electrode group wasmade. In order to examine whether or not a safety valve was broken byapplying vibration to the lid, the lead was joined to the backup lead byultrasonic joining.

(Specimen 1)

A lead used in the battery of the first embodiment and having a shapeshown in FIG. 2 was made using aluminum. Sizes of the lead were: X1 was3.5 mm, Y1 was 25.5 mm, Z1 was 5.5 mm, W1 was 13.5 mm, R1 was 7.0 mm, M1was 0.8 mm, and a thickness was 0.8 mm. X1/Y1 was 0.137.

The lid junctional part of the lead was fixed to the lid by caulkingoutput terminals. Then a current collector tab junctional part of thelead was joined to each backup lead which sandwiched a current collectortab of a positive or negative electrode by ultrasonic joining to make asample.

MODEL 2000 manufactured by Branson was used as an ultrasonic joiningmachine. A joined sample was A1050-H 0.8 mmt, and its horn shape was 2peaks (a pitch of 3.6 mm). A pressure of 450 N was applied, amplitudewas 80%, and a test time (joining time) was 0.5 seconds.

As results of the ultrasonic joining, there was no breakage of a safetyvalve in 100 samples tested.

In addition, resistance values between a center of the lid junctionalpart of the lead and a center of the current collector tab junctionalpart were measured, and an average value thereof was calculated. A valueof 0.13 mΩ was obtained. Test conditions and measurement results areshown in Table 1.

(Specimen 2)

Tests were performed in the same manner as in those for the specimen 1except that a lead having X1 of 5.0 mm and X1/Y1 of 0.196 was used. Asresults of ultrasonic joining, breakage of a safety valve occurred intwo samples of 100 samples tested. The lead had a resistance value of0.12 mΩ. Test conditions and measurement results are shown in Table 1.

(Specimen 3)

Tests were performed in the same manner as in those for the specimen 1except that a lead having X1 of 2.0 mm and X1/Y1 of 0.078 was used. Asfor the specimen 3, tests of 100 samples were scheduled to be performed,but leads were broken in all 30 samples upon ultrasonic joining sincethe test had started, and therefore, the experiment was stopped when the30 samples were tested. The lead had a resistance value of 0.14 mΩ. Testconditions and measurement results are shown in Table 1.

Comparative Example 1

In Comparative Example 1, a lead having a shape shown in FIG. 14 wasused. This lead had a lid junctional part 103 (a), a current collectortab junctional part 103 (b), and a linkage 103 (c) which linked the lidjunctional part 103 (a) to the current collector tab junctional part 103(b), and had a shape which was bent almost at a right angle along a sideseparating the linkage 103 (c) from the lid junctional part 103 (a).

A length A1 of the lid junctional part 103 (a) in a longer direction was20.5 mm, a length A2 of the lid junctional part 103 (a) crossing at aright angle to the longer direction was 7.0 mm, a length B1 of thecurrent collector tab junctional part 103(b) in a longer direction was25.5 mm, a length B2 of the current collector tab junctional part 103(b) crossing at a right angle to the longer direction was 5.5 mm, alength C1 of the linkage 103 (c) in a longer direction was 7.5 mm, alength C2 of the linkage 103 (c) crossing at a right angle to the longerdirection was 0.9 mm, and a thickness was 0.8 mm. C1/B1 was 0.57. Testswere performed in the same manner as in those for the specimen 1 exceptthat the lead having the shape described above was used.

In Comparative Example 1, breakage of a safety valve occurred in 78samples among 100 samples tested. The lead had a resistance value of0.11 mΩ. Test conditions and measurement results are shown in Table 1.

TABLE 1 Pressure Joining X1/Y1 applied Amplitude time Resistance ResultsSpecimen 1 0.137 450 N 80% 0.5 seconds 0.13 mΩ 0/100 pcs occurrence ofbreakage Specimen 2 0.196 450 N 80% 0.5 seconds 0.12 mΩ 2/100 pcsoccurrence of breakage Specimen 3 0.078 450 N 80% 0.5 seconds 0.14 mΩLead was broken upon the ultrasonic joining (impossible to test)Comparative — 450 N 80% 0.5 seconds 0.11 mΩ 78/100 pcs occurrence ofbreakage Example 1

Table 1 shows that the breakage in the specimen 1 and 2 using the leadhaving X1/Y1 within a range of 0.12 or more and 0.2 or less occurredless frequently than in Comparative Example 1, and that the vibrationwas hardly transmitted to the lid. In addition, it was shown that theleads in the specimens 1 and 2 had a resistance value which was almostthe same as that of the lead having no vibration absorber part inComparative Example 1, and a battery performance was not influenced. Onthe other hand, due to the fact that the lead in the specimen 3 wasbroken upon the ultrasonic joining, the results showed that the leadhaving X1/Y1 of less than 0.12 had a low strength.

Experiment 2

Tests were performed in different ultrasonic joining conditions.

(Specimen 4)

Samples were made using the same lead as that in the specimen 1 exceptthat a pressure of 1000 N was applied upon the ultrasonic joining, anamplitude was 90%, and a testing time (joining time) was one second. Asresults of the ultrasonic joining, breakage of a safety valve occurredin three samples among 100 samples tested. The lead had a resistancevalue of 0.13 mΩ. Test conditions and measurement results are shown inTable 2.

(Specimen 5)

A lead used in the battery of the second embodiment and having a shapeshown in FIG. 4 was made using aluminum. Sizes of the lead were: Y2 was5.5 mm, Z2 was 21 mm, W2 was 13.5 mm, R2 was 8.0 mm, Q2 was 8.5 mm, anda thickness was 0.8 mm. Ultrasonic joining conditions were the same asthose for the specimen 4.

As results of ultrasonic joining, there was no breakage of a safetyvalve in 100 samples tested. The lead had a resistance value of 0.15 mΩ.Test conditions and measurement results are shown in Table 2.

(Specimen 6)

A lead used in the battery of the third embodiment and having a shapeshown in FIG. 9 was made using aluminum. Sizes of the lead were: X2 was4.5 mm, and M2 was 5.8 mm. X2/Y2 was 0.818. Other sizes were the same asthose of the lead used in the specimen 5. Ultrasonic joining conditionswere the same as those in the specimen 4.

As results of ultrasonic joining, there was no breakage of a safetyvalve in 100 samples tested. The lead had a resistance value of 0.15 mΩ.Test conditions and measurement results are shown in Table 2.

(Specimen 7)

A lead having the same sizes as those of the lead in the specimen 6except that X2 was 3.0 mm and X2/Y2 was 0.545 was used. Ultrasonicjoining conditions were the same as those in the specimen 4.

As results of ultrasonic joining, there was no breakage of a safetyvalve in 100 samples tested. The lead had a resistance value of 0.16 mΩ.Test conditions and measurement results are shown in Table 2.

(Specimen 8)

A lead having the same sizes as those of the lead in the specimen 6except that X2 was 2.0 mm and X2/Y2 was 0.364 was used. Ultrasonicjoining conditions were the same as in the specimen 4.

As for the specimen 8, tests of 100 samples were scheduled to beperformed, but leads were broken in all 30 samples upon ultrasonicjoining since the test had started, and therefore, the experiment wasstopped when the 30 samples were tested. The lead had a resistance valueof 0.17 mΩ. Test conditions and measurement results are shown in Table2.

Comparative Example 2

Tests were performed in the same manner as those for the specimen 4except that a lead which was the same as that in Comparative Example 1was used. In Comparative Example 2, breakage of a safety valve occurredin all 100 samples tested. The lead had a resistance value of 0.11 mΩ.Test conditions and measurement results are shown in Table 2.

TABLE 2 Pressure Joining X1/Y1 X2/Y2 applied Amplitude time ResistanceResults Specimen 4 0.137 — 1,000 N 90% 1 seconds 0.13 mΩ 3/100 pcsoccurrence of breakage Specimen 5 — — 1,000 N 90% 1 seconds 0.15 mΩ0/100 pcs occurrence of breakage Specimen 6 — 0.818 1,000 N 90% 1seconds 0.15 mΩ 0/100 pcs occurrence of breakage Specimen 7 — 0.5451,000 N 90% 1 seconds 0.16 mΩ 0/100 pcs occurrence of breakage Specimen8 — 0.364 1,000 N 90% 1 seconds 0.17 mΩ Lead was broken upon theultrasonic joining (impossible to test) Comparative — — 1,000 N 90% 1seconds 0.11 mΩ 100/100 pcs occurrence of breakage Example 2

It was shown that the breakage occurred less frequently in the specimen4 than in Comparative Example 2, and even if the ultrasonic joining wasperformed at a high pressure and high amplitude for a long period oftime, transmission of the vibration to the lid could be inhibited.

In addition, it was shown that in the specimens 5 to 7 using the leadhaving X2/Y2 of 0.5 or more, no breakage occurred and even if theultrasonic joining was performed at a high pressure and high amplitudefor a long period of time, transmission of the vibration to the lidcould be inhibited.

On the other hand, due to the fact that the lead in the specimen 8 wasbroken upon the ultrasonic joining, it was shown that the lead having anX2/Y2 of less than 0.5 had a low strength.

Experiment 3

Samples were made in the same flow, using the same leads as in thespecimen 1, the specimen 6 and Comparative Example 1, and whether asafety valve was broken or not upon the manufacturing flow wasconfirmed. Ultrasonic joining conditions were: a pressure of 535 N wasapplied, amplitude was 36 μm, and a joining time was 0.8 seconds at atime. The results are shown in Table 3.

TABLE 3 Pressure The number applied Amplitude Test time of samplesResults Specimen 1 535 N 36 μm 0.8 seconds 500 pcs No safety valve wasbroken at a time by ultrasonic joining Specimen 6 535 N 36 μm 0.8seconds 500 pcs No safety valve was broken at a time by ultrasonicjoining Comparative 535 N 36 μm 0.8 seconds 300 pcs Safety valve wasbroken at Example 1 at a time 102 pcs by ultrasonic joining

As shown in Table 3, in the samples using the leads used in thespecimens 1 and 6, there was no breakage of the safety valve in all 500samples. On the other hand, in the samples using the lead used inComparative Example 1, breakage occurred of a safety valve in 102samples among 300 samples.

Experiment 4 Example 1

Twenty angular nonaqueous electrolyte batteries were produced in thesame manner as in the fourth embodiment. The angular nonaqueouselectrolyte battery had the same structure as that shown in FIG. 10except that a positive electrode terminal 34 was fixed to a lid 33 bycaulking shown in FIG. 11. A plate formed from aluminum alloy ofJIS-A-3003 having a plate thickness of 0.5 mm was used for a container31. A lid formed from aluminum alloy of JIS-A-3003, having a thicknessof 0.2 mm of flange 37, and a total thickness of 1.1 mm was used for thelid 33.

Example 2

Twenty angular nonaqueous electrolyte batteries were produced in thesame manner as those in Example 1 except that the thickness of theflange 37 was changed to 0.4 mm.

Comparative Example 3

A lid 33 on which a flange 37 was not provided, as shown in FIG. 15, wasused. When positive and negative electrode terminals 34 and 35 werefixed in through holes 46 and 38 in this lid 33 by caulking,respectively, parts corresponding to the through holes 46 and 38 on bothsides of the lid 33 in a long side direction were deformed outward, asshown in FIG. 16. As shown in FIG. 17A, the lid 33 whose both sides weredeformed was fitted into an opening part of a container 31. After that,as shown in FIG. 17B, laser seam welding was performed by irradiating alaser beam parallel to a surface at which the side of the lid 33 wasoverlaid on the opening part of the container 31 (i.e., a side wallinner surface) from a tool for welding 45.

Twenty angular nonaqueous electrolyte batteries were produced in thesame manner as those in Example 1 except for the procedures describedabove. A cross-sectional view of the angular battery of ComparativeExample 3, which was cut along a short side direction, is shown in FIG.17C.

As for the batteries of Examples 1 and 2 and Comparative Example 3, anaverage height difference (population parameter n=20) in some spots on atop surface of the lid 33 after laser welding was measured. The spotswhere the height was measured were three spots: a center of the lid 33(for example, a spot C shown in FIG. 17A), one end of the lid 33 in along side direction (for example, a spot A shown in FIG. 17A), and theother end thereof (for example a spot B shown in FIG. 17A). The heightat the spot A and the height at the spot B were compared with the heightat the center C of the lid 33 which was set as a standard. When theheight at the spot A or the spot B was lower than the standard, thedifference was shown as a negative value in Table 4, and when the heightthereof was higher than the standard, the difference was shown as apositive value in Table 4.

TABLE 4 Center of lid Spot A C (standard) Spot B Comparative No flange−0.08 mm   0.00 mm −0.11 mm Example 3 Example 1 Flange 0.2 mm 0.00 mm0.00 mm +0.01 mm Example 2 Flange 0.4 mm 0.00 mm 0.00 mm   0.00 mm

As is apparent from Table 4, in Comparative Example 3 in which the lidhaving no flange was used, the heights at both ends A and B were lowerby about 0.1 mm than that at the center C of the lid which was set asthe standard, and therefore the center C was convexly formed.Additionally, as shown in FIG. 17A, there were gaps between the lid 33and the container 31 because the shape of the side of the lid 33 did notfit with the shape of the opening part of the container 31.

On the contrary, in Examples 1 and 2 in which the lids having the flangewere used, the heights at the spots A and B were within a range of ±0.01mm in both Example 1 in which the flange thickness was 0.2 mm andExample 2 in which the thickness was 0.4 mm, which were excellent.

Experiment 5 Comparative Example 4

As shown in FIG. 18, a lid 33 in which four parts 48 corresponding tothrough holes 46 and 38 on long sides became dented inward, and whichhad no flange 37 was used. When positive and negative electrodeterminals 34 and 35 were fixed in through holes 46 and 38 of this lid 33by caulking, respectively, parts corresponding to the through holes 46and 38 on both sides of the lid 33 in a long side direction wereslightly curved outward, as shown in FIG. 19. As shown in FIG. 20A, thelid 33 whose sides were deformed was fitted into an opening part of acontainer 31. After that, as shown in FIG. 20B, laser seam welding wasperformed by irradiating a laser beam parallel to a surface at which theside face of the lid 33 was overlaid on the opening part of thecontainer 31 (i.e., a side wall inner surface) from a tool for welding45.

Angular nonaqueous electrolyte batteries were produced in the samemanner as those in Example 1 except for the procedures described above.A cross-sectional view of the angular battery of Comparative Example 4,which was cut along a short side direction, is shown in FIG. 20C.

As shown in FIG. 20A, welding defects occurred because there were gapsbetween a side wall around an opening part of the container 31 and thesides of the lid 33.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the inventions. Indeed, the novel embodiments described hereinmay be embodied in a variety of other forms; furthermore, variousomissions, substitutions and changes in the form of the embodimentsdescribed herein may be made without departing from the spirit of theinventions. The accompanying claims and their equivalents are intendedto cover such forms or modifications as would fall within the scope andspirit of the inventions.

1-10. (canceled)
 11. A battery comprising: a container; an electrodegroup comprising a positive electrode and a negative electrode and beingaccommodated in the container; a plurality of current collector tabsextended from a plurality of points of a current collector of at leastone electrode of the positive electrode and the negative electrode inthe electrode group; a lid closing an opening part of the container; alead comprising a current collector tab junctional part connected withthe current collector tabs electrically, a lid junctional part fixed tothe lid, and a vibration absorber part linking the current collector tabjunctional part to the lid junctional part; and a safety valve equippedon the lid; wherein the lead is bent along a first side separating thevibration absorber part from the lid junctional part and a second sidelying adjacent to the first side and separating the vibration absorberpart from the current collector tab junctional part, and has a gapbetween the lid junctional part and the current collector tab junctionalpart.
 12. The battery according to claim 11, wherein the lead comprisesa second vibration absorber part lying adjacent to the second side, andsatisfies the following formula (2):0.5≦X2/Y2≦1  (2) wherein X2 is a length of the second vibration absorberpart in an extending direction of the current collector tab, and Y2 is alength of the current collector tab junctional part in the extendingdirection of the current collector tab.
 13. The battery according toclaim 11, further comprising a middle lead being located between thecurrent collector tab junctional part of the lead and the currentcollector tab.
 14. The battery according to claim 11, wherein thecurrent collector tab is joined to the current collector tab junctionalpart of the lead by ultrasonic joining.
 15. A production method of anangular battery comprising an angular tube-shaped metal container havinga bottom; a positive electrode and a negative electrode accommodated inthe container; a lid placed on an opening part of the container; and aterminal fixed to the lid by caulking and connected to the positiveelectrode or the negative electrode electrically, wherein the lidcomprises a bottom placed in the opening part of the container, and astair part located above the bottom and protruding outward beyond thebottom, the method comprising: placing the bottom of the lid in theopening part of the container accommodating the positive electrode andthe negative electrode, and placing the stair part of the lid on anupper end of a side wall of the container; and irradiating a laser froma direction vertical to a surface at which the stair part of the lid isoverlaid on the upper end of a side wall of the container to weld thestair part of the lid to the upper end of a side wall of the containerby laser welding.
 16. The method according to claim 15, wherein thestair part of the lid has a thickness being the same as or less than awall thickness of the container.
 17. The method according to claim 15,wherein the lid comprises a through hole in which the terminal is fixedby caulking, and a depression at a part corresponding to the throughhole on sides in a long side direction of the lid.
 18. An angularbattery produced by the method according to claim 15.